Hyperspectral Image Analysis in Environmental Monitoring: Setup of a New Tunable Filter Platform

Nowadays, acquisition and analysis of hyperspectral images represent a new frontier among environmental monitoring techniques. Tunable filters and spectrometers, coupled to appropriate sensors, can be used to acquire the spectral information of large areas (more than 10 km2) with great accuracy. The analysis of hyperspectral images provides the spatial distribution (maps) of terrain physical and ecological characteristics. The maps are created by processing the fraction of the incident solar radiation reflected by each object located on the terrain as a function of the wavelength. This feature is known as to “spectral signature”. The aim of the research conducted at DICEA - Sapienza University of Rome is to test the applicability and potentiality of these novel instrumentations to applications in natural and artificial systems. In particular, the environmental status of the region crossed by the Sacco river (Latium, Italy) was investigated by analyzing the spectral response given by tree samples located upstream and downstream an industrial area interested by assessed contamination episodes. Data acquired were synthesized in two reflectance indices related to the chlorophyll content: the normalized difference vegetation index and a modified version. The acquisition campaigns described here have helped the set-up and improvement of the hyperspectral image system based on the use of tunable interference filters. Reflectance values and indices suggest tree samples located upstream the contaminated area are ‘healthier’ than those downstream.